package filter;

import pojo.User;

import javax.servlet.*;
import javax.servlet.annotation.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebFilter(filterName = "LoginFilter",urlPatterns = "/*")
public class LoginFilter implements Filter {
    //过滤器初始化
    public void init(FilterConfig config) throws ServletException {
    }
    //销毁过滤器
    public void destroy() {
    }

    //执行过滤
    @Override
    public void doFilter(ServletRequest request,
                         ServletResponse response,
                         FilterChain chain) throws ServletException, IOException {
        //检查用户是否登录，如果登录，就放行；如果没登录就拦截，让他去登录
        //将request和response类型转换
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        //处理特殊情况：登录，注册，静态文件都不能拦截
        String [] urls = {"/login.jsp","/register.jsp",
                            "/css","images","/js","/login","/user","/verifyCode"};
        //获取当前访问的uri
        String uri = req.getRequestURI();
        for (String u :urls) {
            if (uri.contains(u)){
                //当前访问的是特殊资源
                chain.doFilter(req,resp);
                return;
            }
        }
        //检查Session中是否存放了LOGIN_USER
        HttpSession session = req.getSession();
        User user = (User) session.getAttribute("LOGIN_USER");
        if (user!=null){
            //已经登陆，放行
            chain.doFilter(req,resp);
        }else {
            //如果没登录就拦截，让她登录
            request.setAttribute("LOGIN_MSG","您尚未登录，请去登录");
            request.getRequestDispatcher("/login.jsp").forward(req,resp);
            return;
        }
    }
}
